Intervertebral disc herniation is a troublesome disorder of the spinal column, which can cause pronounced pain and muscle dysfunction, and be debilitating to the patient. Pain from intervertebral disc herniation can last as long as six months and, in very severe cases, for years.
The spinal column is composed of a series of connected bones called vertebrae, which surround the spinal cord and protect it from damage. Nerves branch off the spinal cord and travel to the rest of the body, allowing for communication between the brain and the body. Vertebrae of the spine are connected by spongy intervertebral discs and two small joints called facet joints. The intervertebral discs and facet joints rest between the vertebrae and together allow movement of the vertebrae.
The intervertebral disc is made up of strong connective tissues that hold one vertebra to the next and acts as a cushion or shock absorber between the vertebrae. The intervertebral disc is composed of a tough outer layer called the annulus fibrosus and a gel-like center called the nucleus pulposus. The annulus fibrosus is a strong radial tire-like structure made up of lamellae; concentric sheets of collagen fibers connected to the vertebral end plates. The annulus fibrosus encloses the gel-like nucleus pulposus.
A herniated intervertebral disc can be caused by a sudden back injury or by gradual wear and tear of the disc (also called disc degeneration). As people get older, the center of the disc may start to lose water content, making the disc less effective as a cushion. As a disc deteriorates, the annulus fibrosus can also tear. This can allow displacement of the nucleus pulposus through a crack in the annulus fibrosus, into the space occupied by the nerves and spinal cord. The herniated disc can then press on the nerves (also called pinched nerve) and cause pain, numbness, tingling or weakness in the extremities.
Intervertebral disc herniations may occur in any disc in the spine but herniations in the lumbar and the cervical spine are most common. Disc herniations in the cervical spine may cause radiating pain and muscle dysfunction in the arm, which is generally referred to as cervical rhizopathy. While disc herniations in the lumbar spine may induce radiating pain and muscle dysfunction in the leg, which is generally referred to as sciatica.
Treatments for intervertebral disc herniations include anti-inflammatory medications, such as steroids and non-steroid anti-inflammatory drugs (NSAIDs), physical therapy, behavior modification, intradiscal electrothermal therapy (IDET) and surgery. The surgery can be performed as either an open or mini-open surgery, using very small opening incisions or percutaneously, utilizing specially designed instruments and radiographic techniques.
When herniated discs are surgically treated to remove the herniated portion of the disc annulus, relieving pressure on the spinal nerves, the annulus integrity becomes compromised. This will often result in an annulus fibrosis that may re-herniate, or more likely, will leak nucleus pulposus from the nucleus of the disc, through the weakened zone of the annulus fibrosis, onto the nerve complex surrounding and adjacent to the disc. The nucleus pulposus generates a highly inflammatory response around the exposed nerve complex and causes continued discogenic pain. This phenomenon, sometimes called induced leaky disc syndrome, is a common side effect for procedures that remove the herniated portion of the disc annulus.
There is still a need for new compositions and methods to treat intervertebral disc herniation and the pain and/or inflammation associated with this debilitating condition. New compositions and methods that reduce the size of the disc herniation by enhancing nucleus pulposus resorption would be most beneficial.